project abandoned; migrate to the `aes-siv` crate

The Miscreant project has been abandoned and archived.

The Rust implementation has been adapted into the new `aes-siv` crate which
implements both the AES-CMAC-SIV and AES-PMAC-SIV constructions:

<https://github.com/RustCrypto/AEADs/tree/master/aes-siv>

Please migrate to the `aes-siv` crate.

Alternatively see the `aes-gcm-siv` crate for a newer, faster construction
which provides similar properties:

<https://github.com/RustCrypto/AEADs/tree/master/aes-gcm-siv>